1. Field of the Invention
The present invention relates to a battery pack with a charge and discharge voltage level that changes according to a connected device, an electrical apparatus that includes the battery pack and a battery pack arrangement that includes the battery pack.
2. Description of the Related Art
Recently, usage of portable devices such as mobile phones, PDAs (personal digital assistants), netbooks, laptops, etc. has increased. The portable device is supplied with power by using a rechargeable battery pack including a rechargeable battery that can be repeatedly charged and discharged. The rechargeable battery may be a nickel-cadmium battery, a lead-acid battery, a nickel metal hydride battery, a lithium ion battery, and a lithium polymer battery, which are all commercially available. In the lithium-ion battery, a memory effect is not generated, charge and discharge are free, a self discharge ratio is low, and energy density is high such that the lithium-ion battery is advantageous in aspects of reduced size and weight, and is thereby being widely used.
In general, battery packs of the portable devices are manufactured with different shapes and battery configurations according to a shape of the used device and an operation voltage. Accordingly, the battery pack of an arbitrary device is not used for a different device. This compatibility problem of the battery pack in which a battery pack that may be available cannot be used with other devices generates a waste of resources. Research on a battery pack that may be adaptively used for many different devices is required. The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art as per 35 U.S.C. 102.
What is needed is a battery pack having an extra terminal to sense a voltage needed by a connected electrical appliance and to rearrange the batteries within the battery pack according to the voltage needed by the connected electrical appliance.